1. Field of the Invention
The invention relates to an oscillating system for a mechanical timepiece having an annular balance wheel which is arranged in a fixed manner coaxially on a rotatably mounted balance staff and a helical spring which encloses the balance staff, wherein an inner end of the helical spring is fastened on the balance staff and an outer end of the helical spring is fastened on a fastening device.
2. Description of the Related Art
In known oscillating systems with a regulator, the regulator is mounted in a rotatable manner about the axis of rotation of a balance staff. A balance wheel is rotatably mounted on the balance staff. The length of a helical spring connected between the balance staff and the balance wheel can be regulated by pivoting the regulator. The setting of the frequency, i.e. the daily rate of the timepiece, is performed by changing the direction moment of the helix, that is to say of the torque of the helix upon deflection through 57.296°, corresponding to one rad.
In oscillating systems without a regulator, it is known to set the frequency by changing the mass moment of inertia of the balance wheel. The balance wheel has regulating elements for this purpose. The setting range is small and can thus only be used for precision adjustment. Rough adjustment takes place by the helical springs and the balance wheels being measured on specific instruments and being assigned in relation to one another such that the daily rate of the oscillating system is less than 1 min/day.